WASHINGTON — The last time Republicans in the North Carolina Legislature enacted a law making it harder for some of the state’s residents to vote, a federal court said the statute targeted African-American voters “with almost surgical precision,” and threw it out.

That was last year. Now the legislators are back with a new set of election proposals, and an unconventional plan to make them stick.

Shortly before midnight on Wednesday, Republican senators unveiled legislation that would eliminate the final Saturday of early voting in state elections, a day that typically draws a large share of black voters to the polls. That followed a Republican proposal last week to place a constitutional amendment on the November ballot that would require all voters to display a photo ID before casting votes.

In addition, party leaders say they are preparing a constitutional amendment that would curb the power of the Democratic governor, Roy Cooper, over the state board that controls election procedures.

Since Republicans swept to control of the North Carolina Legislature and the governorship in 2010 and 2012, the state has become ground zero for struggles over election rules and voting rights. But Democrats have recently made gains in the state, most notably with Mr. Cooper’s win in 2016.

Voting rights advocates say Republicans are trying to lock in as much of a political advantage as possible in advance of a November election that could weaken or break their hold on the Legislature.

Gerry Cohen, a longtime counsel to the Legislature who is now a private consultant, said the Republicans were very likely to lose their supermajority in the statehouse. “So they’re trying to pass as much as they can before December 31,” he said.

Tim Moore, the Republican House speaker who sponsored the voter ID amendment, and other party leaders did not respond to calls seeking comment.

Their plan faces risks. Both voter ID and restrictions on early voting were keystone features of the last Republican elections bill, in 2013, that federal judges struck down as racially discriminatory in 2017.

This time, however, the party’s tactics have changed. The voter ID amendment would require approval by citizens as well as legislators. The final Saturday of voting has been popular — nearly 200,000 citizens voted on that day in 2016 — and African-Americans turned out at a rate 40 percent greater than their share of the electorate. But the bill to eliminate that Saturday would apportion those lost hours among other early voting days, so the total hours of polling would not change.

Opponents call that a smoke screen, and say the legislation is crafted to curtail early voting by requiring local election officials to staff every polling place 12 hours a day for all 17 days of the early voting period. Many election offices will struggle to find enough volunteers to meet that schedule, they say, and will be forced to close early voting sites to comply.

North Carolinians call the November vote a “blue moon” election — one in which the only statewide offices on the ballot are comparatively obscure judicial contests. With little to attract voters to the polls, more energized voters are likely to have an even greater impact than usual.

The Republican-led Legislature appears likely to add to the ballot constitutional changes devised to attract conservative voters. The voter ID measure is one. Another would cap the state income tax rate. Still another would make a so-called right-to-work provision part of the state Constitution.

A fourth would guarantee a constitutional right to “hunt, fish and harvest wildlife.”

Mr. Cohen, the consultant, said he believed Republicans may have miscalculated. “They think voter ID will gin up conservative Tea Party turnout,” he said. “I think the effect will be to greatly increase black voter turnout,” given the strong reaction among African-Americans to the 2013 voter ID law.

A version of this article appears in print on , on Page A11 of the New York edition with the headline: In North Carolina, New Tactic To Make Voting Laws Stricter. Order Reprints | Today’s Paper | Subscribe